Affecting more than 1 million Americans, most over age 60 years, Parkinson's disease (PD) is a significantly health concern to gain in this impact give the growth of the geriatric segment of our society. With the recent introduction of therapy aimed at retarding its progression, the early recognition of PD now becomes paramount. Detection of incipient PD would permit the prompt institution of preventative treatment (eg: MAO-B inhibitors or other antioxidants), thus, disease progression might be arrested and its disabling consequences avoided. Hypothesizing that subtle but detectable abnormalities are present early in the illness, we propose to develop a diagnostic test battery for early PD. In an algorithmic fashion, such a test battery might then be employed in the general population, targeting individuals 'at risk' for PD (on the basis of age, family history, biochemical markers, etc.,). Through the use of multi-modality testing, subjects (n=100) with early untreated PD will be examined and compared to non-parkinsonian age and gender matched controls annually for 5 years. The test battery has been specifically assembled based on preliminary work conducted within our PD Research Center and by others. Each of the parameters proposed for study has produced abnormal findings in parkinsonians (early and late disease) as compared to controls. Testing will included olfactory assessment, visual contrast sensitivity measurement, long latency reflex analysis (via mechanical stretch and cutaneous electrical stimulation), reaction time/movement time with determination of movement activation time, tremor as measured by accelerometry, and center of pressure as determined by balance platform testing. Via discriminate analysis and stepwise linear regression modeling, the most sensitive and reliable diagnostic indicators of PD will be determined. This longitudinal controlled investigation of early PD may yield the means by which this degenerative condition could easily detected, thereby affording pre-symptomatic individuals the opportunity for preventative therapy.